Moon's Face Reveals Extreme Cosmic Abuse

A lunar topographic map showing the moon from the vantage point of the eastern limb. In this view, the yellow circles represent some of the 5185 craters equal to or greater than 20 km found on the Moon and counted in this study. Full story.Credit: NASA/LRO/LOLA/GSFC/MIT/Brown

The moon's pimpled face is a testament to the serious
beating it's received over the years from incoming space rocks, and a new study
has found just how severe that lunar smackdown has been.

Scientists have compiled the first comprehensive catalog of
large craters
on the moon to document its cosmic abuse. They've also made a detailed
study of minerals on the moon and identified areas of unusual silica-rich
composition, in a pair of related studies.

"For the first time we're actually detecting how
complex the lunar surface is," said planetary scientist Benjamin T.
Greenhagen of NASA's Jet Propulsion Laboratory in Pasadena, Calif., leader of
one of the mineralogy studies. "It's a bit of a paradigm shift." [See
the new moon map]

The new findings are detailed in threepapers in the Sept. 16
issue of the journal Science.

Mapping the holes

In a second study, scientists built a new lunar crater mapwith data from the Lunar Orbiter Laser Altimeter instrument on NASA's Lunar
Reconnaissance Orbiter,which includes 5,185 craters that are 12 miles (20 km)
in diameter or larger.

The database provides a window on the past, revealing which
parts of the moon are most
pockmarked, and therefore represent older surfaces, and which areas have
been covered over with fresh material by volcanism relatively recently. The
researchers discovered that the moon's oldest regions are the southern near
side and the north-central far side.

One feature, the South Pole-Aitken basin, appears to be the oldest
basin on the moon. As such, it could offer unique clues about the moon's
history, and the story of the early solar system in general.

The findings "are telling us something about the
infancy of the solar system," said the study's leader James W. Head III, a
planetary geologist at Brown University, in a statement. "It is clear we
can find out and learn so much more from future missions, robotic or otherwise.
There is so much to do."

Rare moon minerals

Researchersused the Diviner Lunar Radiometer Experiment,
also on the Lunar Reconnaissance Orbiter, to measure the infrared light coming
from the moon in several frequencies. Long-wavelength infrared light is heat
energy, and it can give researchers information about some of the mineral
content of the lunar surface not available from visual or other-wavelength
observations.

In particular, the scientists looked for areas rich in
silica (made of the chemical compound silicon dioxide), a type of rock that includes quartz and
other formations. This compound is relatively rare on the moon, and requires a particular
volcanic process for creation.

The team found five spots on the moon rich in silica,
showing that this mineral does exist on the moon, but is indeed ?rare.

A third team of researchers, led by Timothy D. Glotch of New
York's Stony Brook
University, honed in on some of these spots and found that the
silica on the moon is likely quartz, silicon-rich glass or alkali feldspar.

"The
silica-rich materials have actually been proposed to be on the surface in these
locations, but we have never sent an instrument that could detect them
before," Greenhagen told SPACE.com. "It's important to know the
silica-rich regions because they require a very specific type of crustal
evolution."